CVE-2021-22873

MEDIUMNVD 6.18.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 8.0 because EPSS predicts 66% probability of exploitation within the next 30 days (top 0.8% of all CVEs). NVD baseline CVSS 6.1 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, nvd
Trending — 3 sources updated this weekElevated
6.1
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 66%
CISA-KEV: Not listedEPSS: 66%CVSS: 6.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Revive Adserver before 5.1.0 is vulnerable to open redirects via the dest, oadest, and/or ct0 parameters of the lg.php and ck.php delivery scripts. Such open redirects had previously been available by design to allow third party ad servers to track such metrics when delivering ads. However, third party click tracking via redirects is not a viable option anymore, leading to such open redirect functionality being removed and reclassified as a vulnerability.

CVSS v3
6.1
EG Score
8.0(high)
EG Risk
67(Track)
EG Risk 67/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity80% × 45%
Exploitation66% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
99.2%
KEV
Not listed

Published

January 26, 2021

Last Modified

November 21, 2024

References (10)

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 10× in last 7d / 31× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 14:15 UTCEPSS rescore
  2. 2026-07-23 01:57 UTCEG score recompute▲ 1.90
  3. 2026-07-22 22:44 UTCEG score recompute
  4. 2026-07-22 14:05 UTCEPSS rescore
  5. 2026-07-21 15:22 UTCEPSS rescore
  6. 2026-07-21 15:22 UTCEPSS rescore
  7. 2026-07-20 17:04 UTCEPSS rescore
  8. 2026-07-19 14:28 UTCEPSS rescore
  9. 2026-07-19 02:52 UTCOSV refresh
  10. 2026-07-16 17:00 UTCEPSS rescore
  11. 2026-07-15 16:55 UTCEPSS rescore
  12. 2026-07-15 16:55 UTCEPSS rescore
  13. 2026-07-15 01:57 UTCEPSS rescore
  14. 2026-07-13 22:27 UTCEPSS rescore
  15. 2026-07-13 22:27 UTCEPSS rescore
  16. 2026-07-12 05:44 UTCEPSS rescore
  17. 2026-07-12 05:44 UTCEPSS rescore
  18. 2026-07-11 08:25 UTCEPSS rescore
  19. 2026-07-09 19:07 UTCEPSS rescore
  20. 2026-07-06 16:25 UTCEPSS rescore
  21. 2026-07-05 02:28 UTCEPSS rescore
  22. 2026-07-05 02:28 UTCEPSS rescore
  23. 2026-07-02 16:57 UTCEPSS rescore
  24. 2026-07-01 15:03 UTCEPSS rescore
  25. 2026-07-01 09:48 UTCOSV refresh
Show 49 more
  1. 2026-06-27 03:06 UTCEPSS rescore
  2. 2026-06-27 03:06 UTCEPSS rescore
  3. 2026-06-25 13:48 UTCEPSS rescore
  4. 2026-06-25 13:48 UTCEPSS rescore
  5. 2026-06-23 21:31 UTCEPSS rescore
  6. 2026-06-23 21:31 UTCEPSS rescore
  7. 2026-06-21 01:58 UTCEPSS rescore
  8. 2026-06-21 01:57 UTCEPSS rescore
  9. 2026-06-19 19:24 UTCEPSS rescore
  10. 2026-06-19 19:24 UTCEPSS rescore
  11. 2026-06-18 17:51 UTCEPSS rescore
  12. 2026-06-18 17:51 UTCEPSS rescore
  13. 2026-06-17 17:51 UTCEPSS rescore
  14. 2026-06-16 17:50 UTCEPSS rescore
  15. 2026-06-15 17:46 UTCEPSS rescore
  16. 2026-06-13 22:58 UTCEPSS rescore
  17. 2026-06-13 15:13 UTCOSV refresh
  18. 2026-06-12 23:10 UTCEPSS rescore
  19. 2026-06-12 23:10 UTCEPSS rescore
  20. 2026-06-11 13:58 UTCEPSS rescore
  21. 2026-06-10 22:16 UTCEPSS rescore
  22. 2026-06-10 22:16 UTCEPSS rescore
  23. 2026-06-07 15:23 UTCEPSS rescore
  24. 2026-06-07 15:23 UTCEPSS rescore
  25. 2026-06-06 13:46 UTCEPSS rescore
  26. 2026-06-06 13:46 UTCEPSS rescore
  27. 2026-06-06 13:46 UTCEPSS rescore
  28. 2026-06-05 22:45 UTCEPSS rescore
  29. 2026-06-05 22:45 UTCEPSS rescore
  30. 2026-06-05 06:09 UTCEPSS rescore
  31. 2026-06-05 06:09 UTCEPSS rescore
  32. 2026-06-05 06:08 UTCEPSS rescore
  33. 2026-06-04 13:10 UTCEPSS rescore
  34. 2026-06-02 20:11 UTCEPSS rescore
  35. 2026-06-02 20:11 UTCEPSS rescore
  36. 2026-05-31 22:29 UTCEPSS rescore
  37. 2026-05-31 22:29 UTCEPSS rescore
  38. 2026-05-29 13:42 UTCEPSS rescore
  39. 2026-05-28 13:43 UTCEPSS rescore
  40. 2026-05-28 13:43 UTCEPSS rescore
  41. 2026-05-27 13:39 UTCEPSS rescore
  42. 2026-05-26 21:38 UTCEG score recompute
  43. 2026-05-26 21:38 UTCGHSA enrichment
  44. 2026-05-26 18:31 UTCOSV refresh
  45. 2026-05-26 13:42 UTCEPSS rescore
  46. 2026-05-26 13:42 UTCEPSS rescore
  47. 2026-05-26 07:17 UTCEPSS rescore
  48. 2026-05-26 07:17 UTCEPSS rescore
  49. 2026-05-24 16:49 UTCEPSS rescore

Publicly available exploits

(2 references)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCK3ysTr0K3R/CVE-2021-22873-EXPLOIT
    First seen Jul 22, 2023

    A PoC exploit for CVE-2021-22873 - Revive Adserver Open Redirect Vulnerability.

    Open source ↗
  • Nucleihttp/cves/2021/CVE-2021-22873.yaml
    First seen Jan 1, 2021

    Revive Adserver <5.1.0 - Open Redirect

    Open source ↗

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-22873?
CVE-2021-22873 is a medium vulnerability published on January 26, 2021. Revive Adserver before 5.1.0 is vulnerable to open redirects via the dest, oadest, and/or ct0 parameters of the lg.php and ck.php delivery scripts. Such open redirects had previously been available by design to allow third party ad servers to track such metrics when delivering ads. However, third…
When was CVE-2021-22873 disclosed?
CVE-2021-22873 was first published in the National Vulnerability Database on January 26, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-22873 actively exploited?
CVE-2021-22873 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-22873?
CVE-2021-22873 has a CVSS v3 base score of 6.1 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.0.
How do I remediate CVE-2021-22873?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-22873, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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